Flora of Clark Valley Area
Flora of Clark Valley Area
This checklist is a start at a flora of the Clark Valley Area. It consists of 157 taxa. Of those 157 taxa, we observed 121 in five different field surveys, and 110 of the 157 taxa have been vouchered here.
The checklist is current as of 30 December 2016, but the following text is from a previous version of this page done in the year 2008.
The floristic area denoted as the Clark Valley Area is delineated by the region outlined in red in the following map:
Only a single road traverses this area, the Rockhouse Canyon Road, on the western side of the Valley (see map below). There is also a private road that accesses private land on the north side of Clark Lake.
The western boundary of this area is the ridgeline / drainage divide of Coyote Mountain and its extension northward, to include the entire drainage basin of Butler Canyon / Rockhouse Canyon up to the San Diego County border with Riverside County.
The eastern boundary is mostly at the 3000 foot elevation contour of the Santa Rosa Mountains. The southeastern boundary is placed just a bit to the west of the Villager Peak Trail and Rattlesnake Canyon, since those two areas are more naturally included in the neighboring floristic area.
The southern boundary is set along Highway S22 to divide Clark Valley from the Badlands. Although this boundary is somewhat arbitrary, S22 gives a well-defined boundary.
For more information about Clark Valley, including pictures from our surveys, see Borrego Desert: Clark Valley.
The voucher search was redone on 24 December 2016. This time only vouchers from Clark Valley itself and the immediately-surrounding areas were accepted. The following text has not been changed from the previous search.
The vouchers come from a search on 8 December 2008 of the Consortium of California Herbaria. The Consortium records were searched for San Diego County specimens that contained the word Clark in the locality (297 vouchers), as well as records with coordinates that fell within a rectangle that encompassed this area (369 vouchers). Duplicate vouchers, vouchers outside this area, and vouchers determined only to the genus that had more than one possible species, were removed.
This process yielded a total of 226 vouchers of 133 unique taxa.
The dominant collectors in the Consortium records were Larry Hendrickson and Kim Marsden and vice-versa, 83 vouchers; R. Mitchel Beauchamp, R. C. Pierce, 71 vouchers; and Bill Sullivan, 31 vouchers. These three sets of collectors accounted for 185 of the 226 vouchers, 82% of the total.
The locations of the vouchers are plotted in the following map, which also shows the boundaries of this region in more detail:
Because many vouchers share the same location, there are far fewer than 226 points plotted above.
Field work has been added from 3/7/09 and 12/19/09, but the following text has not yet been updated.
Three different areas within the Clark Valley area have been field surveyed. On 27 December 2007, James Dillane, Wayne Armstrong and I surveyed the 2.7 miles of the Alcoholic Pass Trail on Coyote Mountain that are on the Clark Valley side. We surveyed only for species not previously found on the southwestern side of the trail, so this survey was very incomplete. That portion of the trail is shown in green on the following map:
On 9 and 12 December 2008, Mike Crouse and I surveyed the two different routes shown in the following map :
We surveyed 5.75 unique miles on 9 December 2008, and 5.7 unique miles on 12 December 2008.
We also scanned the slopes of the nearby portion of the Santa Rosa Mountains for the elephant trees, Bursera microphylla, reported from that location (indicated by the labeled line in the above map), without finding them. However, since those trees were likely to be leafless at that time, they easily could have escaped our binocular survey from afar. This species was added to the checklist below based on sightings by Mark Jorgensen and Larry Hendrickson.
Note added 30 December 2016: We relocated the elephant trees on 19 December 2009 and vouchered one of them; see The Elephant Trees of Clark Valley.
A total of 63 taxa that could be fairly-confidently identified were found in those three December searches; 19 of those 63 taxa, 30%, are not among the vouchered species. A small number of additional taxa were found that could not be confidently identified at those times.
The unvouchered species do not come from any general problem with my identifications, since those unvouchered species include such easy-to-recognize taxa as Opuntia ramosissima, Psorothamnus spinosus, Ferocactus cylindraceus, and Encelia farinosa. This simply reflects the lack of botanical work for this area. It is possible that one or two of the unvouchered species might be misdetermined, since some of those determinations were made from dead plants.
The total number of taxa presented below is 153, 148 of which are native. Of the 153 taxa, 63 were observed on one of the three field surveys, leaving 90 to be found from surveys at a more optimal time of year, or in locations not yet surveyed. Since 30% of the observed taxa are so far unvouchered, this may imply that the voucher list is on the order of 30% incomplete. However, since many of the unvouchered taxa are common, it may only imply that the most common taxa have not yet been vouchered.
Another source of incompleteness for this checklist is that most of the area has never been surveyed, especially the steep lower slopes of the Santa Rosa Mountains which may defy further surveys indefinitely. I estimate at most 24 square miles (62 km2) has had any survey within it, whereas 34 square miles (88 km2) has never had any survey within it. Using the standard relationship that the number of species scales as the 0.3 power of the area, this implies that (58/24)0.3 = 1.30 times more species should be found in the total area of ~58 square miles. This incompleteness is an additional factor to the incompleteness of the surveyed areas.
Thus the checklist below may be on the order of 1 / 1.32 ~ 60% complete, implying that the true number of taxa in this area might be roughly 260 instead of the 153 present below.
Checklist for the Clark Valley Area
This checklist is current as of 30 December 2016.
This checklist is only for a subset of the Clark Valley Floristic Area defined above, of just the floor of the Valley and the immediately-adjacent areas. Rockhouse Canyon / Butler Canyon has its own flora since that area is very different floristically from the desert floor area.
- Notes on the Scientific Names Used At This Site and
- Information about the order in which the species are presented, and the links from the Scientific Name and Common Name.
An asterisk before the common name indicates a non-native species.
The column with header #V gives the number of vouchers in this area.
The column with header #Pls gives the minimum number of observed plants from all the surveys in this area, up to a maximum of 99 plants. An x indicates we have observed that taxon but no abundance estimate was made.
One species, Helianthus niveus ssp. tephrodes, has no entry in either column since it may or may not be present in this area. One voucher from 1933 has a vague location of North Borrego Valley on road to Clark Lake. Another voucher is from just east of this area on S22.
Version for printing, without lines and other text on this page: html (4 pages) or pdf Clickbook booklet (1 double-sided page). (See printing instructions for an explanation of these options)
# Fam Scientific Name (*)Common Name #V #Pls Ferns 1 Pte Cheilanthes parryi woolly lipfern 10 Eudicots 2 Aca Justicia californica chuparosa 1 x 3 Ama Amaranthus blitoides *mat amaranth 20 4 Ama Amaranthus fimbriatus fringed amaranth 1 5 Ama Tidestromia suffruticosa var. oblongifolia Arizona honeysweet 15 6 Apo Asclepias subulata rush milkweed 1 2 7 Apo Funastrum hirtellum rambling milkweed 1 8 Apo Pilostyles thurberi Thurber's pilostyles 3 1 9 Ast Ambrosia dumosa burroweed 5 99 10 Ast Ambrosia salsola var. salsola cheesebush 3 5 11 Ast Baileya pauciradiata Colorado Desert marigold 5 79 12 Ast Bebbia juncea var. aspera sweetbush 2 4 13 Ast Calycoseris parryi yellow tackstem 1 14 Ast Calycoseris wrightii white tackstem 1 15 Ast Chaenactis carphoclinia var. carphoclinia pebble pincushion 2 16 Ast Chaenactis fremontii Fremont pincushion 2 20 17 Ast Chaenactis stevioides desert pincushion 99 18 Ast Dicoria canescens desert dicoria 1 20 19 Ast Encelia farinosa brittlebush 4 20 20 Ast Encelia frutescens button encelia 2 2 21 Ast Geraea canescens hairy desert-sunflower 4 99 22 Ast Helianthus niveus ssp. tephrodes Algodones Dunes sunflower 23 Ast Helianthus petiolaris ssp. canescens gray desert sunflower 2 24 Ast Isocoma acradenia var. acradenia entire-leaved alkali goldenbush 2 25 Ast Isocoma acradenia var. eremophila toothed-leaved alkali goldenbush 1 99 26 Ast Lepidospartum squamatum scale-broom 1 27 Ast Malacothrix glabrata desert dandelion 2 30 28 Ast Monoptilon bellioides desert star 1 x 29 Ast Palafoxia arida var. arida Spanish needle 7 40 30 Ast Perityle emoryi Emory's rock-daisy 1 31 Ast Peucephyllum schottii pygmy-cedar x 32 Ast Pluchea sericea arrow-weed 99 33 Ast Psathyrotes ramosissima turtleback x 34 Ast Rafinesquia neomexicana desert chicory 2 99 35 Ast Stephanomeria exigua ssp. exigua slender wreathplant 1 36 Ast Stephanomeria pauciflora wire-lettuce 1 37 Ast Trichoptilium incisum yellow-head 1 38 Ast Trixis californica var. californica California trixis 1 39 Ast Xylorhiza orcuttii Orcutt's woody-aster 3 40 Big Chilopsis linearis ssp. arcuata desert-willow 3 41 Bor Amsinckia tessellata var. tessellata bristly fiddleneck 1 42 Bor Cryptantha angustifolia narrow-leaved cryptantha 7 99 43 Bor Cryptantha barbigera var. barbigera bearded cryptantha 1 44 Bor Cryptantha costata ribbed cryptantha 4 45 Bor Cryptantha ganderi Gander's cryptantha x 46 Bor Cryptantha maritima Guadalupe cryptantha 5 47 Bor Cryptantha micrantha var. micrantha red-root cryptantha 2 48 Bor Cryptantha nevadensis var. nevadensis Nevada cryptantha x 49 Bor Heliotropium curassavicum var. oculatum seaside heliotrope 2 x 50 Bor Pectocarya heterocarpa chuckwalla pectocarya 2 10 51 Bor Pectocarya peninsularis Baja pectocarya 1 52 Bor Pectocarya platycarpa broad-fruited combseed 1 53 Bor Pectocarya recurvata curvenut combseed 1 54 Bor Phacelia crenulata var. ambigua heliotrope phacelia 1 20 55 Bor Phacelia crenulata var. minutiflora little-flowered heliotrope phacelia 20 56 Bor Phacelia distans common phacelia 2 10 57 Bor Tiquilia palmeri Palmer's coldenia 1 1 58 Bor Tiquilia plicata plicate coldenia 1 59 Bra Brassica tournefortii *Sahara mustard 1 99 60 Bra Dithyrea californica spectacle-pod 2 1 61 Bra Lepidium lasiocarpum ssp. lasiocarpum hairy-podded pepper-grass 3 99 62 Bra Sisymbrium irio *London rocket 2 5 63 Bra Streptanthella longirostris longbeak streptanthella 1 5 64 Bur Bursera microphylla elephant tree 13 65 Cac Cylindropuntia bigelovii teddy-bear cholla x 66 Cac Cylindropuntia echinocarpa silver cholla 3 22 67 Cac Cylindropuntia ganderi Gander's cholla 15 68 Cac Cylindropuntia ramosissima pencil cholla 1 20 69 Cac Echinocereus engelmannii Engelmann's hedgehog cactus 1 70 Cac Ferocactus cylindraceus California barrel cactus 8 71 Cac Mammillaria dioica California fish-hook cactus 1 72 Cac Opuntia basilaris var. basilaris beavertail cactus 1 73 Cam Nemacladus sp. nemacladus x 74 Car Achyronychia cooperi frost mat 4 75 Che Allenrolfea occidentalis iodine-bush 3 99 76 Che Atriplex canescens var. laciniata Caleb four-wing saltbush 1 99 77 Che Atriplex elegans var. fasciculata wheelscale 2 10 78 Che Atriplex hymenelytra desert holly 2 3 79 Che Atriplex lentiformis ssp. lentiformis big saltbush 65 80 Che Atriplex polycarpa cattle saltbush 99 81 Che Monolepis nuttalliana Nuttall's poverty weed 1 99 82 Che Salsola paulsenii *Paulsen's Russian thistle 1 99 83 Che Suaeda nigra bush seepweed 1 99 84 Cle Peritoma arborea bladderpod 1 85 Cle Wislizenia refracta ssp. palmeri Palmer's jackass clover 1 86 Con Cuscuta californica var. papillosa papillate dodder 3 87 Cro Crossosoma bigelovii rock crossosoma 1 88 Eup Chamaesyce micromera Sonoran spurge 1 1 89 Eup Chamaesyce polycarpa small-seeded spurge 1 80 90 Eup Chamaesyce setiloba starfish (Yuma) spurge 1 91 Eup Croton californicus California croton 3 92 Eup Ditaxis lanceolata narrowleaf ditaxis x 93 Eup Ditaxis neomexicana New Mexico ditaxis 1 94 Eup Stillingia spinulosa annual stillingia 7 20 95 Fab Acmispon strigosus strigose lotus 1 96 Fab Astragalus crotalariae Salton milk-vetch 2 99 97 Fab Astragalus didymocarpus var. dispermus dwarf white milk-vetch 1 98 Fab Astragalus lentiginosus var. borreganus Borrego milk-vetch 13 99 99 Fab Dalea mollis silky dalea 1 100 Fab Dalea mollissima downy dalea 1 x 101 Fab Lupinus arizonicus Arizona lupine 1 23 102 Fab Prosopis glandulosa var. torreyana honey mesquite 3 99 103 Fab Psorothamnus emoryi Emory's indigo-bush 7 15 104 Fab Psorothamnus schottii indigo bush 50 105 Fab Psorothamnus spinosus smoke tree 1 106 Fab Senegalia greggii catclaw 20 107 Fou Fouquieria splendens ssp. splendens ocotillo 1 8 108 Ger Erodium cicutarium *redstem filaree 1 10 109 Ger Erodium texanum Texas filaree 1 x 110 Kra Krameria bicolor white rhatany 3 40 111 Lam Hyptis emoryi desert-lavender 2 10 112 Lam Salvia columbariae chia 5 113 Lam Salvia vaseyi Vasey's sage 10 114 Loa Mentzelia affinis yellow blazing star 1 20 115 Loa Mentzelia desertorum desert blazing star 2 116 Loa Mentzelia involucrata bracted blazing star 3 117 Loa Petalonyx thurberi ssp. thurberi Thurber's sandpaper-plant 2 10 118 Mal Eremalche exilis white mallow 2 1 119 Mal Eremalche rotundifolia desert five-spot 1 120 Mal Hibiscus denudatus rock hibiscus x 121 Mal Sphaeralcea angustifolia copper globemallow 1 99 122 Mon Cistanthe ambigua dead man's fingers 1 99 123 Nyc Abronia villosa var. villosa hairy sand-verbena 5 50 124 Nyc Allionia incarnata var. villosa large-flowered trailing four o'clock 1 125 Ona Chylismia claviformis ssp. peirsonii brown-eyed primrose 6 99 126 Ona Eremothera boothii ssp. condensata Booth's evening primrose 2 7 127 Ona Eulobus californicus California suncup 2 99 128 Ona Oenothera deltoides ssp. deltoides dune primrose 3 99 129 Pap Eschscholzia minutiflora ssp. minutiflora small-flowered poppy x 130 Pap Eschscholzia parishii Parish's poppy x 131 Phr Mimulus bigelovii var. bigelovii Bigelow's monkeyflower x 132 Pla Mohavea confertiflora ghost flower 1 133 Pla Plantago ovata desert plantain 6 99 134 Pol Aliciella latifolia ssp. latifolia broad-leaf gilia x 135 Pol Eriastrum eremicum ssp. eremicum desert woolly-star 5 136 Pol Loeseliastrum matthewsii desert calico 1 137 Pol Loeseliastrum schottii Schott's calico 1 99 138 Pol Chorizanthe brevicornu var. brevicornu brittle spineflower 1 3 139 Pol Chorizanthe corrugata wrinkled spineflower 1 x 140 Pol Eriogonum inflatum desert trumpet 1 x 141 Pol Eriogonum thomasii Thomas' buckwheat 2 x 142 Pol Eriogonum trichopes little desert trumpet 20 143 Res Oligomeris linifolia lineleaf whitepuff 5 99 144 Sim Simmondsia chinensis jojoba 1 20 145 Sol Lycium brevipes var. brevipes desert boxthorn 3 99 146 Sol Nicotiana clevelandii Cleveland's tobacco 1 147 Tam Tamarix aphylla *athel 5 148 Tam Tamarix ramosissima *saltcedar 5 149 Vis Phoradendron californicum desert mistletoe 99 150 Zyg Fagonia laevis California fagonia 2 x 151 Zyg Fagonia pachyacantha sticky fagonia x 152 Zyg Larrea tridentata creosote bush 8 99 Monocots 153 Aga Hesperocallis undulata desert lily 2 50 154 Poa Aristida adscensionis six-weeks three-awn 3 155 Poa Hilaria rigida big galleta 2 80 156 Poa Schismus arabicus *Mediterranean grass 1 157 Poa Schismus barbatus *Mediterranean schismus 4 99
Voucher data provided by the participants of the Consortium of California Herbaria (ucjeps.berkeley.edu/consortium/)
Copyright © 2008-2016 by Tom Chester, Mike Crouse, RT and Shaun Hawke, Keir Morse, and John Randall.
Permission is freely granted to reproduce any or all of this page as long as credit is given to me at this source:
Comments and feedback: Tom Chester
Last update: 30 December 2016